Preheat oven to 350°F.
Cream butter and sugar in large bowl at medium speed of electric mixer. Beat in eggs, corn syrup, yogurt and lemon extract. Combine flour, baking powder and poppy seed in a small bowl. Add dry ingredients gradually to butter mixture until combined.
Drop tablespoons of dough onto lightly greased or parchment lined baking sheets.
Bake 10 to 12 minutes until edges just begin to brown. Cool on wire rack.
For Icing: Whisk powdered sugar, lemon juice and lemon extract in a medium bowl until smooth. Transfer icing to resealable plastic bag; snip corner and pipe onto cookies in decorative design. Garnish with finely shredded lemon peel, if desired.